We have found that substituted cephalosporins are potent elastase inhibitors and therefore are useful anti-inflammatory/antidegenerative agents.
Proteases from granulocytes and macrophages have been reported to be responsible for the chronic tissue destruction mechanisms associated with inflammation, including rheumatoid arthritis and emphysema. Accordingly, specific and selective inhibitors of these proteases are candidates for potent anti-inflammatory agents useful in the treatment of inflammatory conditions resulting in connective tissue destruction, e.g. rheumatoid arthritis, emphysema, bronchial inflammation, osteoarthritis, spondylitis, lupus, psoriasis and acute respiratory distress syndrome.
The role of proteases from granulocytes, leukocytes or macrophages are related to a rapid series of events which occurs during the progression of an inflammatory condition:
(1) There is a rapid production of prostaglandins (PG) and related compounds synthesized from arachidonic acid. This PG synthesis has been shown to be inhibited by aspirin-related nonsteroidal anti-inflammatory agents including indomethacin and phenylbutazone. There is some evidence that protease inhibitors prevent PG production; PA1 (2) There is also a change in vascular permeability which causes a leakage of fluid into the inflamed site and the resulting edema is generally used as a marker for measuring the degree of inflammation. This process has been found to be induced by the proteolytic or peptide cleaving activity of proteases, especially those contained in the granulocyte, and thereby can be inhibited by various synthetic protease inhibitors, for example, N-acyl benzisothiazolones and the respective 1,1-dioxides. Morris Zimmerman et al., J. Biol. Chem., 255, 9848 (1980); and PA1 (3) There is an appearance and/or presence of lymphoid cells, especially macrophages and polymorphonuclear leukocytes (PMN). It has been known that a variety of proteases are released from the macrophages and PMN, further indicating that the proteases do play an important role in inflammation. PA1 (1) Recent histochemical investigations showed the accumulation of granulocytes at the cartilage/pannus junction in rheumatoid arthritis; and PA1 (2) a recent investigation of mechanical behavior of cartilage in response to attack by purified elastase demonstrated the direct participation of granulocyte enzymes, especially elastase, in rheumatoid cartilage destruction. H. Menninger et al., in Bioloqical Functions of Proteinases, H. Holzer and H. Tschesche, eds. Springer-Verlag, Berlin, Heidelberg, New York, 1979, pp. 196-206. PA1 (2) chloro or fluoro: PA1 (3) --COOH: PA1 (4) --CHO: or PA1 (5) --CH.sub.2 A wherein A represents PA1 (k) unsubstituted or substituted amino or amido group especially --NH.sub.2, --CONH.sub.2 and N-alkyl or N,N-dialkyl derivatives thereof. PA1 (a) alkanoyloxy especially ##STR5## (b) C.sub.1-3 alkoxy especially methoxy, ethoxy or i- or n-propyloxy; PA1 (c) halo; PA1 (d) hydrogen; PA1 (e) hydroxy; PA1 (f) substituted or unsubstituted mercapto; or PA1 (g) carbamoyloxy, especially L- or D- form of ##STR6## PA1 (a) hydrogen; PA1 (b) hydroxy; PA1 (c) mercapto; PA1 (d) substituted oxy; PA1 (e) substituted thio; PA1 (f) hydrocarbyl or substituted hydrocarbyl group; PA1 (g) cyano; PA1 (h) carbonyl or thiocarbonyl containing substituents bonded by said carbonyl or thiocarbonyl radical; PA1 (i) halo; PA1 (j) phosphono or a substituted phosphono group. PA1 (1) hydroxy; PA1 (2) OR.sub.1, where R.sub.1, represents hydrocarbyl group; PA1 (3) C.sub.1-6 alkylthio; PA1 (4) C.sub.1-6 alkylsulfinyl; PA1 (5) C.sub.1-6 alkylsulfonyl; PA1 (6) halo such as fluoro, chloro, bromo or iodo; or; PA1 (7) hydrogen; or PA1 (9) C.sub.1-6 alkyl. PA1 (1) C.sub.1-3 alkyl; PA1 (2) hydroxy; PA1 (3) OR.sub.1 'where R.sub.1 ' is p2 (a) C.sub.1-6 alkyl especially methyl, ethyl, n-propyl; PA1 (4) halo especially Cl or F; or PA1 (5) --SO.sub.2 R. PA1 (a) straight or branched chain alkyl having from 1 to 20 carbon atoms, ethyl, isopropyl, t-butyl, pentyl or hexyl; PA1 (b) aryl having from 6 to 10 carbon atoms; PA1 (c) cycloalkyl having from 3 to 8 carbon atoms; PA1 (d) alkenyl having from 2 to 20 carbon atoms; PA1 (e) cycloalkenyl having from 5 to 8 carbon atoms; PA1 (f) alkynyl having from 2 to 20 carbon atoms; PA1 (g) alkoxy having from 1 to 10 carbon atoms; PA1 (h) aralkyl, alkaryl, aralkenyl, aralkynyl, alkenylaryl or alkynylaryl wherein alkyl, aryl, alkenyl and alkynyl are as previously defined; PA1 (i) loweralkenylalkyl; PA1 (j) alkanoylalkyl; PA1 (k) alkanoyloxyalkyl; PA1 (m) alkanoyloxy; PA1 (n) a heterocyclic group including heterocyclic alkyl or heterocyclic alkenyl. PA1 (1) aralkyl; PA1 (2) aryl; PA1 (3) straight or branched loweralkyl; PA1 (4) straight or branched loweralkenyl; PA1 (5) cycloalkyl; PA1 (6) alkanoyloxyloweralkyl; PA1 (7) alkanoylloweralkyl; PA1 (8) alkoxyloweralkyl; or PA1 (9) haloalkyl; and PA1 (1) benzyl; PA1 (2) ethyl; PA1 (3) t-butyl; PA1 (4) --CH.sub.2 CH.sub.2 CH=CH.sub.2 or --CH.sub.2 CH=C(CH.sub.3).sub.2 ; PA1 (5) --CH.sub.2 CH.sub.2 CH.sub.2 COOt-Bu; PA1 (6) alkanoyloxymethyl; or PA1 (7) alkanoylmethyl. PA1 (1) hydrogen; PA1 (2) C.sub.1-6 alkyl especially methyl, ethyl, isopropyl, n-pentyl or n-hexyl; PA1 (3) halo C.sub.1-6 alkyl especially chloro or fluoro C.sub.1- 6 alkyl; or PA1 (4) hydroxy C.sub.1-6 alkyl; PA1 (5) methylene or substituted methylene especially C.sub.1-6 alkylmethylene, unsubstituted or substituted phenylmethylene, phenylthiomethylene, phenylsulfinylmethylene or phenylsulfonylmethylene; PA1 (6) C.sub.1-6 alkoxy C.sub.1-6 alkyl; PA1 (7) unsubstituted or substituted benzyl; or PA1 (8) unsubstituted or substituted phenylthio C.sub.1-6 alkyl, phenylsulfonyl C.sub.1-6 alkyl; PA1 (9) unsubstituted or substituted phenoxy C.sub.1-6 alkyl or PA1 (10) unsubstituted or substituted phenylamino C.sub.1-6 alkyl PA1 (1) hydrogen; PA1 (2) C.sub.1-6 alkyl; PA1 (3) substituted or unsubstituted methylene; PA1 (4) unsubstituted or substituted phenylthio C.sub.1-6 alkyl or phenylsulfonyl C.sub.1-6 alkyl. PA1 (1) hydrogen; PA1 (2) methyl, ethyl or i- or n-propyl; PA1 (3) methylene; or PA1 (4) phenylthiomethyl or phenylsulfonyl methyl. PA1 (1) A compound of formula (I) is treated with a lower alkanol, a substituted or unsubstituted benzyl alcohol, or a substituted or unsubstituted benzhydrol (diphenylmethanol) in the presence of a catalyst such as sulfuric acid, hydrochloric acid and any one or a combination of the acid illustrated below in Table I: PA1 at from about 0.degree. to about 150.degree. C. with or without refluxing until the esterification is substantially complete. Optionally, a solvent may be used to facilitate the reaction. The common solvents used are benzene, toluene, xylene, sulfolane-xylene, diethylether, tetrahydrofuran, 1,2-dimethoxyethane, dioxane and the like; PA1 (2) A compound of formula (I) is converted to an acid halide such as acid chloride or bromide via treatment with a halogenating agent such as thionyl chloride, phosphorus penta- or oxychloride followed by reaction with an appropriate alcohol; and PA1 (3) Other methods such as alkylation of carboxylate salts (e.g., K.sup.+, Na.sup.+, Ca.sup.++, Ag.sup.+, Cu.sup.+, tetralkylammonium-R.sub.4 N.sup.+, and Hg.sup.++ salts) of formula (I) with alkyl halides, for example, benzylchloride, benzyhydryl chloride; reaction with alkyl isoureas; treatment with diazomethane or diazophenylmethane (C.sub.6 H.sub.5 CHN.sub.2); alcoholysis of anhydride derived from the cephalosporin acid corresponding to formula (I); transesterification with t-butyl esters or isopropenylacetate and the like may also be used. These methods are disclosed in Saul Patai, editor, The Chemistry of Functional Groups, Supplement B, The Chemistry of Acid Derivatives, pp. 411-436, John Wiley & Sons, Chichester-New York-Brisbane-Toronto, 1979, and are incorporated herein by reference.
In general, proteases are an important family of enzymes within the peptide bond cleaving enzymes whose members are essential to a variety of normal biological activities, such as digestion, formation and dissolution of blood clots, the formation of active forms of hormones, the immune reaction to foreign cells and organisms, etc., and in pathological conditions such as the degradation of structural proteins at the articular cartilage/pannus junction in rheumatoid arthritis etc.
Elastase is one of the proteases. It is an enzyme capable of hydrolyzing the connective tissue component elastin, a property not contained by the bulk of the proteases present in mammals. It acts on a protein's nonterminal bonds which are adjacent to an aliphatic amino acid. Neutrophil elastase is of particular interest because it has the broadest spectrum of activity against natural connective tissue substrates. In particular, the elastase of the granulocyte is important because, as described above, granulocytes participate in acute inflammation and in acute exacerbation of chronic forms of inflammation which characterize many clinically important inflammatory diseases.
Proteases may be inactivated by inhibitors which block the active site of the enzyme by binding tightly thereto. Naturally occurring protease inhibitors form part of the control or defense mechanisms that are crucial to the well-being of an organism. Without these control mechanisms, the proteases would destroy any protein within reach. The naturally occurring enzyme inhibitors have been shown to have appropriate configurations which allow them to bind tightly to the enzyme. This configuration is part of the reason that inhibitors bind to the enzyme so tightly (see Stroud, "A Family of Protein-Cutting Proteins" Sci. Am. July 1974, pp. 74-88). For example, one of the natural inhibitors, .alpha..sub.1 -Antitrypsin, is a glycoprotein contained in human serum that has a wide inhibitory spectrum covering, among other enzymes, elastase both from the pancreas and the PMN. This inhibitor is hydrolyzed by the proteases to form a stable acyl enzyme in which the active site is no longer available. Marked reduction in serum .alpha..sub.1 -antitrypsin, either genetic or due to oxidants, has been associated with pulmonary emphysema which is a disease characterized by a progressive loss of lung elasticity and resulting respiratory difficulty. It has been reported that this loss of lung elasticity is caused by the progressive, uncontrolled proteolysis or destruction of the structure of lung tissue by proteases such as elastase released from leukocytes. J. C. Powers, TIBS, 211 (1976).
Rheumatoid arthritis is characterized by a progressive destruction of articular cartilage both on the free surface bordering the joint space and at the erosion front built up by synovial tissue toward the cartilage. This destruction process, in turn, is attributed to the protein-cutting enzyme elastase which is a neutral protease present in human granulocytes. This conclusion has been supported by the following observations:
Accordingly, an object of this invention is to discover new protease inhibitors, especially elastase inhibitors, useful for controlling tissue damage and various inflammatory or degenerative conditions mediated by proteases particularly elastase.
Another object of the present invention is to provide pharmaceutical compositions for administering the active substituted cephalosporin sulfoxides as protease inhibitors.
Still a further object of this invention is to provide a method of controlling inflammatory conditions by administering a sufficient amount of one or more of the active, substituted cephalosporin sulfoxides in a mammalian species in need of such treatment.